1. Field of the Invention
The present invention relates to a gas control valve in a water heater.
2. Description of the Related Art
Generally, a storage type closed vessel gas water heater of a flame-retention for automatically controlling the temperature of hot water in a tank to a predetermined level has a gas control valve consisting mainly of a main valve V and a pilot valve V1 arranged along two parallel axes (See FIG. 8).
However, the main valve V and the pilot valve V1 of such a conventional gas control valve are arranged along two parallel axes and their layout may be limited in design. Also, the valves V and V1 along the two axes are actuated with a couple of corresponding cam members 3 and 3xe2x80x2 of a main cam 3a and a pilot cam 3b respectively. This may increase the number of the components and require more labor for assembly. Moreover, the gas control valve itself will be increased in the size and the cost.
It is thus an object of the present invention to provide a gas control valve in a water heater which has a pilot valve and a main valve arranged along a single axis thus to eliminate the foregoing drawbacks.
For achievement of the above object, a gas control valve in a water heater defined in claim 1 of the present invention comprises a pilot valve and a main valve aligned along one axis and arranged operable with an ignition knob for opening and closing, wherein the pilot valve and the main valve are opened in this order and closed in reverse order.
Also, a gas control valve in a water heater defined in claim 2 is a modification of the gas control valve according to claim 1, which further comprises: a cam member mounted on an operating shaft provided with the ignition knob and having a pilot cam surface, a main cam surface, and an extinction cam surface thereof aligned in one track; and a valve pin having the pilot valve fixedly mounted on the distal end thereof, the main valve slidably mounted thereon below the pilot valve, and a main valve opening collar plate fixedly mounted thereon below the main valve as spaced by a given distance from the main valve, and arranged for engagement at the proximal end with the cam member, wherein the valve pin is moved forward and backward by the action of the cam member determined by a program so that the pilot valve and the main valve aligned along the axis of the valve pin can be opened in this order and closed in reverse order in response to the movement of the ignition knob for turning on and off the combusting action.
Since the gas control valve in the water heater according to claim 1 of the present invention has the pilot valve and the main valve aligned along single axis for being opened and closed in response to the operation of the ignition knob, its components can be minimized in the number and the pilot valve and the main valve can be assembled in a unit. Accordingly, while its assembling procedure is improved, the gas control valve will be minimized in the overall size and the cost. Moreover, its layout unlike any conventional two-axe arrangement will be less limitative.
The opening action of the pilot valve always precedes the opening action of the main valve. Also, the closing action of the pilot valve is always preceded by the closing action of the main valve. This allows the water heater to be controlled safely and precisely for supply of fuel gas to turn on and off the combustion.
According to the gas control valve in a water heater defined in claim 2 of the present invention, the cam member having the pilot cam surface, the main cam surface, and the extinction cam surface thereof arranged along one track is fixedly mounted on the ignition operating shaft equipped at the proximal end with the ignition knob and also arranged for direct engagement with the proximal end of the valve pin which has the pilot valve fixedly mounted on the distal end thereof, the main valve slidably mounted thereon below (on the left as shown in FIG. 1) the pilot valve, and the main valve opening collar plate fixedly mounted thereon below (on the left as shown in FIG. 1) the main valve as spaced by a given distance from the main valve so that the valve pin can be moved forward and backward by a predetermined sequence of actions of the cam member to open and close the pilot valve and the main valve aligned along the axis of the valve pin. More particularly, the pilot valve and the main valve are opened in this order and closed in reverse order for turning on and off the combustion. As the ignition knob is turned, the cam member turns and its cam surfaces drive the valve pin to move forward and backward according to a predetermined program thus to open and close the pilot valve and the main valve for controlling the supply of fuel gas to turn on and off the combustion. Accordingly, the gas control valve defined in claim 1 of the present invention will be implemented without difficulty.